On her standard 8v Digi , it runs sweet , starts and ticks over etc lovely , and heats up normally with the stat opening and fan cutting in as it should . However the temp gauge doesn't rise and the warning light flashes all the time , IIRC its a slow flash for low coolant level and a faster one for overheating? This is a pretty fast flash. Where do I start looking? It doesn't have the newer blue temp sender , so obviously I must get one of those.. what colour wires are on that one?
1st thing bridge the pins on the temp sender plug if its a 2 pin 88spec, or earth the red/yel wire if pre88 spec. gauge should shoot to max, if not the wiring is damaged or you have faulty clocks
It's a '90 RJ , and I just knew you'd be the first to reply! Purely out of nosiness.... how did you become so talented at VAG electrics?
I taught myself! spent ages nosing thru diagrams and researching in the various vag forums oh! and check the earth to the sender is ok. it should earth back behind the fusebox somewhere, so put a multimeter on continuity mode and check between the brown wire and battery -ve.
Thanks , I'll check that . Yeah , I remeber the first time I tried deciphering a Haynes mk1 Wiring diagram... I had to wire the complete wiper circuit of a mk1 external to the (corroded) fusebox , to get the car to an event...fun. What colour are the wires on the plugs , and how do you know if they've been mixed up? Neither is blue at the mo...
mk2 haynes even worse as all mixed up with loads of diagrams missing! its hard to follow wires to the relavant circuit track if that circuit track doesnt exist or its competly in the wrong place dash temp is a black sensor with a red/yellow and brown wire, ecu temp is blue with a green/brown and white/brown wire
bridged the wires , and sure enough the needle went to the top.... so the gauge must be ok? New sensor ordered , but the red light is still flashing? what sets that off?
the level sender inside the header tank if one is fitted. the light is both an overheat and level warning. it can be the temp sensor fails in such a way that it triggers the light even if temp reads normal,. this happened in my mates mk2 and it took me ages to figure out
I got rid of my coolant lever. It had disintegrated in the tank. So I brought a tank without the level sensor void.
if you do the above then bridge the pins on the old plug to disable the warning on a 90spec. on pre-90 you can just remove the #42 or 43 level sensor control relay
New sensor , and pins bridged on the header tank...........and the light still flashes . Gauge rises as it should now though . The car is actually a 1990 registered , which being an Irish one could very well mean it's a 89 build . It does have the coolant level sensor wiring though.... unless someone added it in afterwards? How do you tell a pre 90 from a post 90? also , ignition on , the light flashes briefly , then goes out as it should , start the car , and leave idling and the light starts flashing after about 18-20 secs , regular as clockwork . I assume the level switch is linking an earth , not a feed?
where is hazard switch, dash or column? if dash look abovbe fusebox for a relay number 42 or 43. pull that out and this will disable the level warning entirely. if on the column you haver a broken level sensor wire, or dash is buggered
Ive got the exact same problem with my 90 spec 8v, changed the temp sender light still comes on like you the only thing i am yet to check it the earth at the back of the fuse box, my next step was to try another set of clocks? Who manufactured the clocks in a 91 spec 8v?
I don't know tbh I had a quick look and the earths seem ok she says the hazard switch is on the column.
okidoki then, dead dash or wiring. if you check out my fusebox faq you can see the 2 pins on fusebox for level sensor, if you stuff a bit of wire into the back across the pins and see if that sorts it. this is how the mk2 carbys were from new! if that sorts it then you just need to do the same thing but more permanent. or whip out all the lighting loom to find the problem but you'll probably find if a wire has snapped it'll be near the header tank, so i would pop the header tank off its brackets and check the wire over where it comes out of the main loom looking for obvious damage. also follow the loom from there back to the brake servo area too, look for any spots that are crimped or chaffed. if its a later 90 then the loom will all be wrapped in tape rather than chunky plastic which probably has all fallen off, leaving wiring exposed to damage. last thing you want to do is bypass the sensor thinking all is well, then whatever damaged the wire carry on and do worse damage to the loom. a few years back i was chatting to tim (aquavalver) who mentioned after a paint job in the engien bay he kept blowing headlight fuses. so i goes to look and find the shop had left the lighting loom on driver chassis leg unsecured and it was sat on the waterpump, slowly getting chopped thru! lucky for him it had only damaged fused circuits, if it had cut into say dim dip resistor wires that would have been his headlight switch and loom on fire
